A mechanical behavior of tissues inside a biological body such as a headache, a bedsore or a pulmonary thromboembolism may be a cause of decreasing a biological function inside the biological body. The headache is caused, when a pulse displacement of blood vessels becomes larger than that caused under a nor mal condition and the adjacent nerves are irritated. The bedsore and the pulmonary thromboembolism (an economy class syndrome) are caused when blood flow in the blood vessels is restricted by a continued load.
A technique for preventing such decrease of a biological function caused by a mechanical behavior of tissues inside a biological body is desired.